Furnace for enameling metal ware



Oct. 1-2 1926. 1,603,014

H. c. BEASLEY El AL I FURNACE FOR ENAMELING METAL WARE Fi l ed 001.1 1, .1923 s Sheets-Sheet 1 ff -56 ww e 7 120 2 a Jaw b u gczz Oct. 12 1926.

H. C. BEASLEY ET AL I FURNACE FOR ENAMELING METAL WARE Filed Oct. 1, 1923 s Sheds-Sheet 2 [nvenfons 7'2, 0

At t rngy fi ot. 12 ,1926. H. C. BEASLEY El AL FURNACE FOR ENAMELING METAL WARE Filed Oct. 1, 1923 G'Sheets-Sheet 4 Fly. 8. G5

a H gm H I Jittorneg s Oct- 12 1926. 1,603,014

H. C. BEASLEY ET AL FURNACE FOR ENAMELING METAL WARE Filed 001;. l. 1923 6 Sheets-Sheet 5 Inven i0 725' ferZerf 6.366652% Jfczcgaa Oct. 12 1926.

H. C. BEASLEY ET AL FURNACE FOR ENAMELING METAL WARE Invnab 'iled Oct.

i 4 ll i Patented Oct. 12, 1926.

UNITED STATES 1,603,014 PATENT OFFICE.

HERBERT c. BEAsLEY, or OAK PARK, AND ROBERT aAeDoUGALL, 0F DOWNERS GROVE, ILLINOIS, ASSIGNOR S, BY MESNE ASSIGNMENTS, '10 BEEMACK FURNACE comPANY, A CORPORATION 01 ILLINOIS.

FURNACE FOR ENAMELING METAL WARE.

Application filed October 1, 1923. Serial No. 665,763.

Our invention relates to improvements in furnaces adapted particularly for treating, fusing and enameling metal ware, though, of course, our furnace might be adapted to other purposes;

In the manufactureof enamel ware such as kitchen utensils and the like, the metal body is first stamped or drawn out in the usual manner to proper shape. The shapes thus produced are more or less covered with grease and oil, as a result of their passage through the dies, and the treatment they receive during their conforming and manufacturing stages. These blanks before being enameled are cleaned or pickled in a dilute acid solution and later in a soda solution to clean them off completely.

The cleaned form is then dipped in the liquid enamel and after the enamel has drained off and been allowed to dry, the material is supported on a fork or carrier of some. kind and conveyed into the fusing furnace which may be coal or oil fired or electrically heated. The door is closed and in the course of a very few minutes, the enamel is fused and the material which then is red hot'is taken out of the furnace and allowed to cool.

' and variations of the temperature in difl'erent parts of the furnace which result in rad1- This prpcess is repeated, there being one, two or three coats or layers of enamel applied as the case may be.

,7 Experience shows that the temperature and the time of this process is of the utmost importance and that the constant opening and shutting of the door of the furnace gives variations in temperature from tlIIlGtO t me cal changes in the product and cause a very large proportion of seconds to .be produced. Seconds are also produced as efresult of careless handling bythe operator whe may drop the fork too rapidly and cause' marking or distortion of the utensil and otherwise damage it, and it is likely to happen because the operator is compelled to exercise care and'skill in handling the material to be treated at aplace where with the furnace door open, heat and breathing conditions are very tryin and it is necessary for him to do it rapidlybecause if the door stays open long, fatal temperature changes in the furnace may take place.

We propose in our new device to provide a furnace wherein the objects beingtreated 5 or fused can be started on their way as soon as they have been dipped or slushed, can 'be dried, pro-heated, fused and cooled during their continuous passage through the furnace wherein the articlesbeing treated ca'n'fifl be placed on the support which' will carry them to and hold them in the furnace without undue haste or crowding of the operator and at a place where it is sufficiently cool for the operator to work himself at maxi? mum efliciency. y

We propose to provide a furnace wherein there will be two parallel lines of articles passing through in opposite directions. The actual furnace where fusing takes place will 7 have a separate chamber for each line, the 3 balance of the furnace where heatin and drying takes place, will be so arranged that the articles heing in the same chamber, the red hot articles from the fusing zone will 7 pass out adjacent the articles going in so that the residual heat from the fused articles will assist in drying and pre-heating thoseartieles on their way.

Experience has shown that it is very imual and smooth fashion into and through the furnace, as if undue; vibration takes place, it will result in marking the enamel by the supporting tools and thus produce seconds. This makes it impossible to operate successfully with a conveyor which .passes through the heated portion of the furnace because such aconveyor cannot be made satisfactorily smooth in operationand we-propose therefore to'have our conveyor outside of the furnace, preferably on the top with supporting hooks passing down through a continuous slot in the furnace to carry the tools or racks which support the work. We associate with the conveyor chain an articulated closure which travels with the chain'and closes the slot, this closure takes the form of a series of channel sections pivoted together, the downward extended flanges of the channel riding oneither side of the slot in a sand bath, thus effectually retaining the heat in the furnace.

We illustrate our invention as applied to an electric furnace but it will be understood, of course, that it might equally well be ,used

in connection with oil, gas, or even coal fire furnaces.

Our invention is illustrated more or less diagrammatically in the accompanying drawings, wherein- Figures 1, 2, and 3 form together a plan view of the entire furnace, the figures going from right to left;

Figure 4 is a side elevation of one end of the furnace;

Figure 5 is a side elevation showing a continuation of the furnace from the left of Figure 4;

Figure 6 is a section of the burning chamber along the line 66 of Figure 2;

Figure 7 is a cross section at the back stay of the burning chamber, along the line 7-7 of Figure 2;

Figure 8 is a section along the line 88 of Figure 2;

Figure 9 is a section along the line 99 of Figure 1;

Figure 10 is a horizontal section portion of the drying and preheating chamber showing doors;

Figure 11 is a detail of the conveyor chain;

Figure 12 is a section along the line 12.12 of Figure 11;

Figure 13 is a plan View in part section of the conveyor chain.

Like parts are indicated by like characters throughout thespecification-and drawin s.

a is a burning chamber of an electric ceramic furnace. This chamber is made up of a concrete base A a bri'ck foundation and outer wall A A an insulating lining A A located at both sides and the bottom, a fire brick floor A fire brick lining walls A and a fire brickcentral partition wall A with the air space between. This divides the burning chamber into two separate parallel zones. Both these zones are covered by fire tiles A A which rest upon the side and partition walls held in place by the vertical columns A and cross beams A The fire tiles A, A areseparated immediately above the center line of each of the two firing zones, there being a narrow slot B located between these fire tiles. B B is a cement filling resting on the fire tiles and forming a continuation of the walls of the slot. B B are channel irons resting on the cement and furnishing with their opposed upwardly extending flanges the upper ter- "minal boundary of the slot, the outer higher arms of the channels form the walls for a reservoir in which an insulating powder B is kept. This powder is preferably held in place by a thin, flat plate B and the channels B B thus are filled with sand 13*". -B B are cast metal web frames associated with the cross beams A and the tiles and 'otherassociated parts supporting the chan:

nels B so as to tie all the parts together and increase their structural strength. Electric heating units not here specifically illustrated will be placed inside the heating zones in the burning chamber and will serve to heat the entire interior of the furnace. The usual type of heating unit might be used, but we prefer to use electric heating units. As shown in Figures 6 and 2 these units are indicated by the letters'C.

\Ve shall now describe the general arrangement of our oven. As indicated in Figures 1, 2, and 3, which as above pointed out form together a general plan View of the furnace, there are provided two drying chambers D, D. These chambers are the first into which the material being heated passes and the last from which the heated material passes. The endless chain conveyor which overlies the entire furnace carries material through the entire furnace. The conveyor chain passes above these chambers. The chambers D, D are open and are preferably not provided with partitions other than the necessary supporting members for the roof, which are here indicated as'the columns D, D. Thus the cold material entering comes in close relation to the heated material leaving and it is dried, and to some extent heated by the heat escaping from the heated matcrial.

Located between the chambers D, D and the central burning chamber A are two preheating chambers E, E. These chambers are preferably somewhat wider than the chambers D, D and are provided with center supporting columns E E which are placed so close together that they form in effect a partition wall provided with frequent openings. The entering material passing in one direction is further dried and is pre-heated by the escaping heat from the already treated material which is moving in the opposite direction. I

From the chambers E, E the material as it is fed in moves from each end into the burning chamber A above described. F is an endless chain conveyor which carries the material through the furnace. At-earh end of the furnace there is mounted a vertical shaft F having the sprockets F which are engaged by the chain F and by means of which the chain is driven. At the upper end of one of the shafts F is mounted a bevel gear F. This gear meshes with a pinion F which is secured to the shaft F upon which is mounted a worm wheel not shown. Beneath this wheel and meshing with it is a worm not shown. The worm is secured to the shaft F at the end of which is mounted a pulley F which may be driven by any suitable power. At the opposite end of the furnace the other shaft F =is mounted upon a frame F which is mounted for slid ng movement. This frame is moved by means chambers of the screw F and the adjustment of the screw moves the frame and so moves the shaft F in and out with reference to the shaft F at the other end of the furnace. By means of this adjustment slack in the chain may be taken up or the chain may be loosened.

All of the chambers of the furnace are formed generally of a masonry structure provided with insulating material and supported and held together by metallic members. The central or burningchamber has, as above described, cross members A and vertical columns A It is further reinforced by longitudinal tie rods A and is provided, preferably adjacent its center, with doors A, A which may be opened for the purpose of cleaning the furnace or for any other reason.

Extending fromend toend of the furnace and through alljof the chambers is the pair of'slots B through which the material carrying hangers, which are attached to the chain F extend downwardly into the furnace. this construction will be described later.

. The pre-heating chambers E, E- are each provided similar to those shown inthe burning chamber and the chambers D, D are similarly constructed. Y I

The openings from each of the drying D, D to the adjacent .pre-heatin chamber. E are providedwith closures These doors are mounted-for vertical movement and are shown in Figure 10 in section and "in elevation in,-'Figure 8, wherein the-left hand door is shown in the raised or closed positiomand the right hand door notchor opening G 1 The notch is to permit the chains Gr G till is in the lowered or open position- Each door is provided in its, upper side with a urpose of this hoomembers depending from the chain F to pass through even if the chain "he accidentally started when the doors are closed. The doors are raised and lowered by means -of pairs of about a wheel G Gr which are carried in pairs on shafts GGr on the topof'the structure. At the outer end 'of each shaft is a sprocket wheel G which is rotated :by means of a chain G which may be moved by any'suitable power. By this means the doors are raised and lowered whenever desirable.

Adjacent the doors G and in-the sides of each of the drying chambers is a pair of observation doors H. These doors are mount- .ed in the side ofthe drying chamber and are preferably hinged. They are rovided with one or more sight holes H w ich are covered with glassgmica or some other transparent material and through them the o erator may look into the furnace. In t e general plan view, shown in Figures 1, 2,

The details of with metallic structural members- Each of these chains-passes and 3, the operating mechanism for the doors G has been omitted. The doors H are preferably lined with .a heat resisting lining such as asbestos, which is shown in Figures 8 and 10-as H As also shown in Figure 10, small metal doors I are provided adjacent the large sliding door G4 downwardly depending hangers J. These hangers may be of different lengths, as shown" in Figure 4, and are mounted in the chain F so as to prevent their swinging with relation to it. Where the links J are to be fastened to the chain F, an additional member J is secured to one of the links of the chain. This member is provided at its upper surface with a notch or groove J in which: the laterally bent upper end J 3 of the member J may lie. is provided with a downwardl boss J which is provided wit perforation J Into this perforation the upper end of the member J is inserted, and

. after being so inserted its upper end J is to fit into the groove J laterally bent so as For carrying certain classes of material, we support, from the hook members J, racks K as showrr in Figures 5 and 4. Across these 'racks are placed knife edged receiving bars K and upon them material to bev heated is supported. Still another arrangement consists of placing across the hook members J, rods K. Uponlthese rods articles having handles, as shown in Figure 4, are .sus; pended. Additional hook members may be suspended and additional articles suspended below them. 1 Above the slot The member J depending a vertical B, through the upper surv face of the furnace, is mounted a double track L. This track is suspended by means of U shaped members L from the varibus structural cross members of the furnace proper. At suitable intervals throughout the length of the chain, additional links M are attached. These links are provided with upwardly extending arms M which carry bearings M in which is journaled a shaft M which carries a pair of rollers M.

By means of these rollers the chain and its lead are supported from the track. 4 In order to prevent upward escape of heat through the slot B from the furnace, and in order'to prevent heating of the track, the chain and the rollers, means are provided for sealing the heat within the furnace. Adjacent each slot on either side of it and running parallel to it, is placed the trough or chain.

channel B These troughs or channels are filled with sand B? or any suitable similar material. Fastened to the links of the chain is a plurality of generally U shaped heat sealing members 0. These members are fastened preferably to the lower links of the Each is formed with downwardly depending sides 0 O and each of these sides is provided at its forward end with a bevelled edge shear 0 The members 0 are arranged to overlap each other at their contacting ends and each is provided at its rear on its outer side with a notch 0 into which the forward outer side of the following member fits when the chain is running substantially straight. When it is bent it takes on the general shape shown at the left of Figure 13 and the members are then not in complete contact, but since the chain is bent only at its ends, which are outside of'the furnace proper, no escape or loss of heat can thus take place.

In Figure 7 is shown, on an enlarged scale, a cross sectional view taken at a point a few feet removed from the section shown in F igure 6. It illustrates particularly the back stay of the burning chamber. F astened to the cross beams A and to the vertical column A are cast web members B. Fastened to the cross member A are other cast web members B For any given cross member there will be two members Band one member B The trough or channel members B which hold the insulating sand B are secured to and supported by members B or B. The fire brick lining walls A and the the doors G.

fire brick partition walls A are carried above and are carried upward so that the members B and B are in contactwith them. 7

In the section shown in Figure 8 the construction of the dryingchamber'just before the pre-heating chamber is shown. Vertical columns Qare provided and a cross beam Q rests uponthem. The member Q} also carries the mechanism for raising and lowering The members Qand Q form a part of the structural framework-of the pre-heating chamber. The structural frame work of the drying chamber is formed of similar members, that is to say of columns R and cross beams R Secured to the column B and the cross beams R are web members R and secured to the cross beam R at its center is a web R To these members the channels 13 are secured in the same manner as that described above for the mounting of the channels'B on the-members B and B.

Since the temperature in the drying chamber is much lower than. that in either the pre-heating or burning ehamber, the construction is simpler and less provision is made toprevent loss of heat. All of'the. chambers of the furnace are carried on the higher degree of heat. built of comon brick U, the inner wall 15,

same concrete foundation A which extends from end to end of the furnace. Resting 011 the columns D and extending across the furnace to each of; the slots are a plurality of supporting bars R preferably two are provided to rest on each column. Opposite these bars and forming in effect a continuation of them at either end is mounted a short supporting bar B. This bar is supported on the column R and is secured to it and is additionally braced and supported by a gusset plate R.

Extending longitudinally of thefurnace drying chamber and resting upon the s upporting members R and R are a plurality of roof supporting bars 5 which are preferably T shaped as shown. The wall of the furnace is built of common brick S and this wall extends across the bottom of the fur- A Within the furnace drying chamber and spaced inwardly away from the brick wall S is agmetallic sheath S The space between the sheathing S and the brick wall S is filled with insulating material S This material may be put in any form but we prefer to use powdered insulating material. The floor of the furnace drying chamber above the common brick floor is made up of insulating material S which is preferably placed in brick form. The inner roof of the furnace. drying chamber is formed of common brick S which is supported upon the bars S. At intervals between the cross beams R throughout the length of the drying chambers, web members T are supported from the members R and R They rest directly upon the low gitudinal members S and upon the slot line ing angles T To their upper surfaces the sand troughs B are secured and; they thus serve additionally to support such troughs.

As shown in Figure 10, the construction of the walls in the pre-heating chamber differs from that of the walls of the drying chamber in that it is calculated to stand a The outer wall is built of fire brick U and the space between the two walls is filled in with insulating material U This material may be of any form but we have found it most convenient to use insulating brick.

Although we have shown an operative form of our invention, still it will be obvious that many changes in size, shape, and arrangement of parts may be made without departing from the spirit of our invention, and we wish therefore that our showing be taken as in a sense diagrammatic.

The use and operation of our invention is as follows:

When the furnace is to be used, the burning chamber is heated by means of the heating units within it. When it'has been raised to the desired degree of heat and it is desired to commence operation,'the outer doors of the furnace and the doors between the chambers of the furnace will normally be open. Material to be treated isplaced 'on the carrying chain at each end. .As shown in Figure 1 there is a loading point marked X to the right and as shown in Figure 3 there is a loading point marked Y tothe left. Opposite each of these points at the same end is a corresponding unloading point.

The chain is driven and carries material ZlI1-' to the furnace from each end, additional material being fed onto the. chain as it travels into the furnace. As material reaches the heating chamber and then moves out from it, the heat from the heated mate- .rial affects the incoming material and so in the drying chamber material freshly enter-- continuous operation, the conveyor moving constantly. No doors which must be opened and closed during the operation are present and to a very large extent the heat absorbed by the material as it is burned is not Wasted or lost but is utilized in drying and preheating the incoming material.

the treated material we permit it to cool gradually and so return it to the open air substantially cool and thus prevent the incommunicating each with j'uriouseifect which generally ensues where highly heated material is suddenly transferred into theopen air.

l/Ve claim: 1. A furnace comprising a central heat.- ing chamber, a pair of pre-heating chambers located one at either end of the heating chamber, and a pair of drying chambers one of the pre-, heating chambers, the central chamber being formed into two separate chambers, the pre-' heating and drying chambers being formed each in one chamber.

2. A furnace comprising a central heating chamber, a pair of pre-heating chambers located one at either end of the heating chamber, and a pair of drying chambers communicating each with one of the preheating chambers, the central chamber being formed into two separate chambers, the preheating and drying chambers. being formed each in one chamber, the furnace being open at its ends to the air.

operation of our furnace, we are able to treat articles to'be heated in a,

Further than this, by thus absorbing the heat from ber,

.municating each with one of the pre-heating 3. A furnace comprising a central heating chamber, apair of pre-heating cham bers located one at either end of the heating chamber, and a pair of drying chambers communicating each with one of the preheating chambers, the central chamber being formed into two separate chambers, the pre-heating and drying chambers being formed each in one chamber, the furnace being open at its ends to the air, the chambers opening freely intoeach other.

4. A furnace comprising a central heating chamber, a pair of pre-heating chambers located one at either end of the'heating chamber, and a pair of drying chambers communicating each with one of the pre heatingf chambers, the central chamber being formed into two separate chambers, the

pre-heating and drying chambers being i formed each in one chamber, in combination with a conveyer located outside of the furnace, the furnace being provided with a continuous opening and said conveyer adapted to support material through said opening and to convey the samewithin and through said furnace and means for preventing the escape of heat through saidopening.

5. A furnace comprising a central heating chamber, a pair of pre-heating chambers located one, at either end of the heating chamber, and a pair of drying chambers communicating each with one of the pro-heating chambers, the central chamber being formed into two separate chambers, the pre-heating. and drying chambers being formed each in one chamber, the furnace being'open at its ends to the air, in combination with a conveyer located outside of the furnace, the

furnace being provided with a continuous opening and said conveyer adapted to support material through said opening and to convey the same within and through said furnace and means for preventing the escape of heat through said opening.

6. A furnace comprising a central heating chamber, a pair of pro-heating chambers located one at either end of the heating chamand a pair of drying chambers comchambers, the central chamber being formed into two separate chambers, the pre-heating and drying chambers being formed each in one chamber,'the furnace beingopen at its ends to the air, the chambers opening freely into each other, in combination with a conveyer, located outside of the furnace, the furnace being provided with a continuous opening and said conveyer adapted to support material through said opening and to convey the same within and through said furnace, and means for preventing the escape of heat through said opening.

7. A furnace comprlsmg a central heating chamber containing a heat source, a pair of pre-heating and cooling chambers located one at either end of the heating chamber, and a pair of drying and cooling chambers, the central chamber being composed of two separate chambers in parallel, each of them communicating with the pre-heating 1 and cooling chambers, a conveyer located outside of the furnace, the conveyer comprislng an endless belt, there being two parallel slots through the furnace to permit the passage of material in opposite directions through the furnace, a closure for the slot comprising a sand bath and an articulated channel carriel by the conveyer having its flanges trave ling in the sand bath on either side of the slot,

8. A furnace comprising a heating chamber, a pair of pre-heating and cooling chambers, and a pair of drying and cooling cham bers, the central chamber being composed of .two separate chambers each of them communicating with the pre-heating and cooling chambers, cross sectional area of the furnace being largest at the center and smallest at the ends, a conveyer located outside of the furnace, the furnace being slotted to permit a portion of the conveyer to pass down into the furnace, the conveyer comprlsing an endless belt having two branches both of them overlying the furnace, there being two parallel slots through the furnace to permit the passage of material in opposite directions through the furnace, a closure for the slot comprising a sand bath and an articulated channel carried by the conveyer having its flanges travelling in the sand bath on either side of the slot..

9-'In combination with a'furnace, a conveyer adapted to convey material 'therethrough, the conveyer being outside of said furnace, said furnace provided with an opening adjacent said conveyer and means for preventing the escape of heat from said opening, said means comprising sand troughs on either side of said opening and an articulated moving shield surmounting said opening provided with downwardly depending edges engaging the sand of said trough and adapted to move therethrough in response to the movement of the conveyer, said shield being formed of a plurality of sections, each adapted to overlap the end and rear it and provided with forward side. 1

10. In combination with a furnace, a con veyer adapted to convey material therethrough, the conveyer being outside of said furnace, said furnace provided with an opening adjacent said conveyor and means for preventing the escape of heat from said opening, said means comprising sand troughs on either'side of said opening and an articulated moving shield surmounting sharpened edges in its sides of the one ahead of said opening provided with downwardly -depending edges engaging the sand of said trough and adapted to move therethrough in response to the movement of the conveyer, said shield being formed of a plurality of sections, each adapted to overlap the end and rear sides of the one ahead of it and provided with sharpened edges in its forward side, and provided with a notch in its rear to permit overlapping with one side of the member directly in its rear.

11. In combination, a furnace, an endless chain conveyer located outside of said furnace, a slot in said furnace beneath said chain, and an articulated hood overlying said slot and secured to said chain, said hood being formed with a plurality of hood members secured to separate links of the said chain, said hood members adapted to overlap so as to provide a complete hood when the chain is running straight, and adapted to move with the chain links in response to bending movement of the chain.

12. In combination, a furnace, an endless chain conveyer located-outside of said furnace, a slot in said furnace beneath said chain, and an articulated hood overlying said slot and secured to said chain, said hood being formed with a plurality of hood members secured to separate links of the said chain, said hood members adapted to overlap so as to provide acomplete hood when the chain is running straight, and adapted to move with the chain links in response to bending movement of the chain,

each of said hood members provided with sharpened forward edges, and each pro vided in its outside rear with a notch into which the corresponding edge of the following hood member is received when the chain is running straight.

13. In a furnace, a chamber adapted to be heated to a comparatively low degree of heat, said furnace formed with an outer shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and said brick shell being filled with loose insulating material.

14. In a furnace, a chamber adapted to be heated to a comparatively low degree of heat, said furnace formed with an outer .shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and said brick shell being filled with insulating material, in combination with columns spaced apart within said chamber, and metallic roof supporting members carried by said columns to assist in supporting the roof of said furnace.

15. In a furnace, a chamber adapted to be heated to a. comparatively low degree of heat, said furnace formed with an outer shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and said brick shell being filled with insulating material, in combination with columns spaced apartv within said chamber, and metallic roof supporting members carried by said columns to assist-in supporting the roof of said furnace, some of said metallic members being carried directly upon said columns and extending transversely of said furnace, secondary metallic members resting upon said first metallic members and extending longitudinally of said furnace.

16. In a furnace, .a chamber adapted to be heated to a comparatively low degree of heat, saidfurnace formed with an outer shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and said brick shell being filled with insulating material, in combination with columns spaced apart within said chamber, and metallic roof supporting members- ,carried by said columns to assist in supporting the roof of'said furnace, some of said metallic members being carried directly upon said columns and extending transversely of said furnace, secondary metallic members resting upon said first I metallic members and extending longitudinally of said furnace, and additional transverse metallic members carried by the side walls of said furnace and supporting tudinal members.

17. In a furnace, a chamber, said furnace formed with an outer shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and said brick shell being filled with insulating material, and a metallic reenforcing structure comprising vertical columns and cross members, this metallic structure relieving the furnace proper of all but its own weight.

18. In a furnace, a chamber, said furnace formed with an outer shell of common brick and inner metallic lining spaced away therefrom, the space between said lining and sai brick shell being filled with insulating material, in combination with columns spaced apart within said chamber, and metallic roof supporting members carried by said columns further longito assist in supporting the .roof of said furnace, and'a metallic reenforcing structure sgomprising vertical columns and cross memers, furnace proper of all but its own weight.

19. In a furnace, a chamber, the furnace proper being formed of a common brick shell and provided with a lining shell of fire brick spaced away therefrom, the space between the said shells being filled with heat insulating material, the roof of said furnace being formed of fire tile which carries further heat insulating material above it, and a metallic reenforcing and supporting structure formed in combination with said furthis metallic structure relieving the nace proper, said reenforcing structure comprising vertical columns and horizontal cross members supported thereby, the said structure reinforcing the furnace and aconnace proper,- said reenforcing structure relieving the furnace proper of the burdenof all but its own weight.

21. In a furnace, the furnace structure proper built of ceramic material, in combination with a reenforcing metallic structure, the furnace being provided with an opening through which a conveyer, situated on the outside thereof, carries material within the furnace, a conveyer for carrying said material, and means for preventing the loss of heat through said opening, said metallic structure supporting the weight of said conveyer and of said heat insulating means.

22. In a furnace, the furnace structure proper built of ceramic material, in combination with a reenforcing metallic structure, the furnace being provided with an opening through which a conveyer, situated on the outside thereof, carried material within the furnace, a conveyer for carryingsaid material, and means for preventing the loss of heat through said opening, said metallic structure adapted to support the weight of said conveyer and of said heat insulating means, there being associated with said metallicstructure, and carried thereby, a plurality of attaching members carrying the heat insulating means. I Y

- 23. In combination with a furnace, a conveyer adapted to operate above a heated zone, means on said"conveyer for preventing the escape of heat from said zone, said means including an articulated inverted trough supported from said conveyer, said conveyer formed for lateral curving, the members of said articulated trough overlapping when the conveyer is straight and having relative movement conforming to the movement of said conveyor when the same is curved. I

24. In combination with a, furnace provided withan opening, a conveyer. adapted to operate over said opening, means on said conveyor for preventing the escape of heat from said opening, said means including an articulated. in erted trough supported from veyer for conveying material therethro'ugh,

the conveyer beingoutside of said furnace,

said furnace provided with an opening ad and means for pre-- jacent said conveyer, venting the escape of heat from said'opening, said means comprising sand troughs on either side of said opening and an articulated moving shield surmounting said opening provided with downwardly depending edges engaging the sand of said trough and moving therethrough in response to the movement of the conveyer, said shield being formed of a plurality of sections, each overlapping'the end and rear sides of the one ahead of it and provided with sharpened edges in its forward side, said articu-- lated hood being attached to and carried by a flexible chain, said chain being driven by a wheel, the hood members having relative movement in response to the bending of the chain about said wheel.

26. In combination with a furnace, a conveyer for conveying material therethrough, the conveyer being outside of said furnace, said furnace provided with an opening adjacent said conveyer and means for preventing the escape of heat from said opening, said means comprising sand troughs on either side of said opening and an articulated moving shield surmounting said open-. ing providd'with downwardly depending edges engaging the sand of said trough and adapted to move .therethrough in response to the movement of the conveyer, said shield being formed of a plurality of sections, each overlapping the endand rear sides of the one ahead of it and provided with sharpened edges in its forward side, and provided with a notch in its rear to permit overlapping with one side of the member directly in its rear, said articulated hood being attached to and carried by a flexible chain, said chain being driven by a wheel, the hood members being mounted for relative movement in response to bending of the chain about said wheel.

27. In combination, a furnace, an endless chain conveyer located outside of said furnace, a slot in said furnace beneath said chain. and an articulated hood overlying said slot and secured to said chain, said hood being formed with a plurality of hood members secured to separate links of the said chain, said hood members adapted to overlap so as to provide a complete hood when the chain is running straight, and moving with the chain links in response to bending movement of the chain, said articulated hood section extending longitudinally from each end of the duplex firing chamber provided with goods conveying means movable in opposite directions,

end sections forming preheating zone.

29. In an oven of the class described, the walls of which form open at its opposite ends and in which are formed a pair of slots extending from end to end of said passage, means for heating said passage about midway the ends there- 'of, an endless conveyor chain forming a loop, the sides of which are substantially parallel 'to each other and to said slots and which are outside said passage, the ends of a combined cooling and each of which passesthrough one of the firing zones, each of said an elongated passage the loop extending substantially beyond the open ends of said passage, means for supporting and driving said conveyor chain and supports for material to be heated carried by said conveyor and arranged thereon so as to travel in said slots and extend into said passage.

30. In an oven of the class described, the walls of which form an elongated passage open at its opposite ends and in which are "formed a pair of slots extending from end to end of said passage, means for heating said passage about midway the ends there of, an endless conveyor chain forming a loop, the sides of which are substantially parallel to each other and to said slots and which are outside said passage, the ends of the loop extending substantially beyond the open ends of said passage, means for supporting and driving said conveyor chain and supports for material to be heated carried by said conveyor and arranged thereon so as to travel in said slots and extend into said passage, and flexible covering means carried by the conveyor chain extending over the slot and adapted to close the same and prevent the escape of heated air there through.

31. In an oven of the class described, the walls of which form an elongated passage open at its 0 posite ends and in the roof of which are ormed a pair of slots extending from end to end of said passage, means for heating said passage about midway the ends thereof, an endless conveyor chain forming a loop, the sides of which are substantially parallel to each other and to said slots and which are outside said passage,

the ends of the loop extending subst antially Signed et Chicago, IlL, thie 12- day of beyond the open ends 3f said pasfiage, means September, 1923.

for supporting and rivi ng sai 'con'veyor chain and supports for material tq be heated d g f g a f 5 carried by said conveyor land arranged Se gfif f 1S 0 thereon so as to travel in said slqts and p v extend into said passage. 7 ROBERT MAGDOUGALL. 

